Query Processor Of The Embedded Active Real-time Database ARTs-EDB

As the core technique of mobile-computing, mobile-commerce and informative electrical appliances, the Embedded Database Management System appears recently which is a newly data management technology. The EDBMS which based on the mature technology of DBMS and aimed at the idiographic embedded system and device, implements the embedded system data storage, data organization, data management.ARTs-EDB is an embedded active real-time database, needs the main-memory database system (MMDB)'s support, and MMDB insures that the transaction has no I/O access in its running time. Having the characters of flexibility, briskness and good migration, the multi-thread and modularized process structure and transaction execution model meets embedded micro-kernel construction, which is the foundation of the whole system construction.Query processing is one of database's kernel module, ARTs-EDB's query processing is integrated by many query techniques of traditional database and memory-resident database(MMDB), and it has taken a full consideration of embedded system's features. And we advance the pipeline executing mode by combining the multi-thread technique and point materialization technique, which greatly improve the executing performance and reduce the memory consuming.According to the MMDB's features, the join tree and costly factors are analyzed, and then we get the dynamic programming searching algorithm based on the specified join tree type and the cost formula which adapt to ARTs-EDB. As some application programs(especially periodic transaction) may be executed many times, it is necessary to provide a cache to save query plans to avoid syntax parsing and query optimizing many times. It resolves the problem effectively.